HIV/AIDS Glossary

Phase 1 Trial

Phase 1 Trial

The first step in testing an experimental drug (or other treatment) in humans. Phase 1 trials evaluate the drug's safety and toxicity at different dose levels and determine drug pharmacokinetics. Because little is known about the possible risks and benefits of the drug being tested, Phase 1 trials usually include only a small number of participants (approximately 20 to 100). Testing of other biomedical interventions, such as diagnostic tests or medical devices, also begins with Phase 1 trials.